The present invention relates to a technique for use in the manufacture of a semiconductor device; and, more particularly, the invention relates to a technique that is effective for application to a wiring process that includes a step of burying a conductive film, that is made mainly of aluminium (Al), inside an opening for wiring.
The wiring technique studied by us is, for example, as set out below. Initially, an opening for wiring is formed in a semiconductor substrate, after which a titanium (Ti) film, for example, is deposited on the semiconductor substrate, including the inside of the wiring opening. Subsequently, an aluminium film, for example, is deposited on the titanium film at low temperatures and high power to a relatively large thickness (e.g. about 200 nm). Thereafter, the semiconductor substrate is maintained at high temperatures (e.g. about 400° C.) until the aluminium film is deposited to a desired thickness (e.g. about several hundreds of nanometers). The high temperatures are kept continuously over several minutes to cause reflow of the aluminium film, thereby causing the opening to be buried therewith.
A wiring technique is set out, for example, in Japanese Laid-open Patent Application No. 2001-267569. In this application, a technique is disclosed wherein a source electrode of a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is constituted of a barrier layer that is made, for example, of titanium tungsten, titanium nitride (TiN) or the like, and this barrier layer is built up with pure aluminium thereon, so as to prevent a failure from occurring upon ultrasonic wire bonding.